Shaker conveyors



Dec. 4, 1956 E. R. BERGMANN SHAKER CONVEYORS 4 Sheets-Sheet l Filed July l1, 1952 NWN 'III

RMN @man NUN MSN NkQN M mw M HMM NQ L M w@ Dec. 4, 1956 E. R. BERGMANN 2,772,770

SHAKER CONVEYORS Filed July 11, 1952 4 Sheets-Sheet 2 VELOCITY gg/ TANK vALvE msPLAceMENT OPENS 9 suv: Ran a Moves cYc Lr. '1 closes PRESSURE TANK VAI-VE YEN V OPE N f -2 CLOSED -n SLAVE VALVE RerRAcTs PRESSURE com-szon. VSSS PREssMANK y/ao'efw" o. so. m. m. my fa/'f/a/egywm Dec. 4, 1956 E. R. BERGMANN 2,772,770

SHAKER coNvEYoRs filed July 11, 1952- 4 sheets-sheet 3 man? f 7m? mi.;

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Dec. 4, 1956 E. R. BERGMANN SHAKER CONVEYORS 4 Sheets-Sheet 4 Filed July 11,-1952 NNN 1 @NN 1N NNN .M

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United States Patent SHAKER coNvEYoRs Ernst R. Bergmann, Evergreen Park, Ill., assgnor to Goodman Manufacturing Company, Chicago, Ill., a corporation of Illinois Application July 1 1, 1952, Serial No. 298,263

15 Claims. (Cl. 198-220) This invention relates generally to improvements in shaker conveyors, and more particularly to a shaker conveyor of the type employing a` reciprocating flexible steel belt instead of the usual connected trough pans.

Heretofore shaker conveyors for transporting material, such as in a coal mine or the like, have employed trough pan lines which are composed of troughing sections capable of being bolted together. Reciprocating motion is given to the pan line by a shaker drive, which gives the pan line a reciprocating motion whereby material is transported therealong from` the inby end to the outby end where the material is discharged generally vupon a moving belt conveyor or other shaker conveyors. The trough pans are mounted upon frames held in position by jacks bearing against the mine roof, ball frames being interposed between the pan line and the mounting frame so that the pan line can have reciprocating movement. As the working face is advanced additional trough pans must be added to the pan line, so that gathering and loading equipment or a continuous miner at the working face can discharge its contents directly onto the shaker pan line.

The addition of such trough pan sections to the pan line has required brief shutdowns, and in order to avoid such shutdowns it has been proposed that a-exible steel belt supported upon troughing rollers be substituted for the trough pan sections. However, such belt troughing is able to withstand tensile stresses only, and when the shaker drive pushes on the belt in one direction of its motion, the belt will collapse or buckle.

Heretofore, in order to place the belting under tension at all times the outby end thereof has been connected to suitable spring means to impose such tension. Such tensioning arrangements, however, have imposed an inordinate load upon the shaker drive, since it must not only'transport the material but must also work against the force of such springs.

. In carrying out the present invention, an inby shaker drive is mounted upon a mobile inby unit having crawler treads. The inby unit supports the belt for reciprocat ing movement and a reel of additional belting, so that as the working face is advanced the inby mobile unit may move upon its crawler treads toward the working face and pay out an additional length of belt. The belt. is connected to an outby unit which is arranged to place.. tension on the belt only during the carrying portion of -the stroke thereof, such tension being removed during the back stroke of the belt when the shaker drive is pulling upon the belt, and when the belt moves relative to the material being conveyed thereon. The inby mobile unit is arranged with a gripping mechanism which moves *withv a frame supporting the belt and reciprocating under the influence of the shaker drive. The mobile inby unit is also arranged so as to transmit a signal therefrom to the outby unit so that the outby unit will place a tension upon the belt during movement of the belt in the outby direction.

The invention is further characterized by means 1o- Patented Dec. 4, 1956 ICC cated on the outby unit which is sensitive to the ncreased displacement of the tensioning'means as would be occasioned by a change in load on the belt or by a change in position for some unintended reason of either the outby unit orY the inby unit or both. In carrying out the invention the outby unit is also arranged'to transmit a signal back to the inby unit whereby the position of same may be corrected by causing the motors turning the crawler treads tooperate at low speed.

With the foregoing considerationsin mind it is a principal object ofv this invention to afford an improved shaker conveyor which employs a exible steel belt for the troughing pan, and to afford mechanism whereby the troughing belt need be subjected to tension to stiften same only during the portion of thecyele of re'- ciprocating movement thereof when the belt is transporting material.

Another object is to afford a construction for a shaker driven flexible trough whereby the flexible trough`is tensioned properly by tensioning means operable when the llexible trough is moving in a direction as would tend to cause collapse of same.

Another object Yis to afford-a construction lfor a shaker conveyor of the type employing a reciprocating steelv belt wherein a suitable signal will be transmitted from one unit thereof to another unit thereof to'indicate a need for the change in positioning of the "s'aid--one unit so as to maintain the correct tension upon the lbelt at all times', Other vobjects andimportant features ofi the invention will be apparent from a study of the following speciication taken with the drawings which: together Vshow a preferred embodiment of the invention, andwhatis now considered to be the best mode of practicing the principles thereof. Other embodiments of 'theinvention -will be suggested to those having the benefit of the teachings herein and it is therefore intendedthatfthe invention not be limited by the precise embodiment shown and described, nor otherwise than by the scope and purview of `the claims subjoined.

In the drawings: f

Fig. l is a front elevation view of a shaker conveyor having embodied therein the improvements according to the present invention; Y

Fig. 2 is an 4enlarged front elevation view of a portion of the outby endof the lconveyor shown in Fig. 1, showing details of a fluid pressure operated ,cylinder and a lluid pressure system therefore for placing tension upon the troughing belt of such shaker conveyorj Fig. 3 is an enlarged detailed front elevation view .of thegripping mechanism mounted on the inby end of the shaker conveyor shown in Fig. l; i"

Fig. 4 is a velocity-time curve showing the velocity of the troughing belt vduring various portions of its cycle;

Fig. 5 is a displacement-time curve to the` same abscissae scale as Fig.` 4, and showing the relationship thereof to the control of pressure to the operatingcylinder shown in Fig. 2; v

Fig. 6 isa diagram showing the operating cycle obtaining in the application of pressure fluid to the actuating cylinder shown in Fig. 2, the scale of ordinates thereof corresponding to the scale shown in Fig. 5; Y

Fig. 7 is a somewhat schematic view of the outby end of the shaker conveyor shown in Figi l, and showing means for receiving a signal from the inby end ofthe conveyor, and also showing means for transmitting a signal from the outby conveyor unit to the inby conveyor unit; l

Fig. 7A is a schematic view .of part of the inby -end of the conveyor unit shown in Fig. lvshowing means for transmitting a .signal to the outby conveyor unit, and` also showing a circuit for controlling the drive motors of the inby unit, said motors being also controlled in outby roonveyoriunit; t

Fig. 8 is a plan view of the outby unit, showing th manner in which the flexible Vsteelgbelt istconnected thereto; I-Tig. `9 is asec'tion .taken along -theiline39-g9 `taf-Fig. -2 lookin g Ain y.the -dieetion vof the arrows,` and showin g` fthe ma.' ner of 4attaehvrrient `the piston rdl'qf vthe actuating VcylinderLto-thetroughspau ofthefoutby-unitf Y' "X10-lis a sectioi1taken along the'sline Jlll-d10 of Fig lookingginithe direction of thearrows; `and i Eigf-l-:l sisfari enlarged front elevationview of a transmitting selsyn motorshown' inlFg. "1.

Referring now particularly toFig 1 of vvthe vdraws/ings the '-fimproied shakerconveyor v-accc'irdinfg Ito the :present conven'tioncorisiusts of 'a nobile"fin-by unit referred -.t0 Igeherallybylthe reference `'numeral 121 and an outby unit referred toig'ener'ally by the reference fnumeral'22. The mobile"sinby tunitVZl @affords a means lot' support sfora 'flexible usteel .conveyor 'belt :233 which is also supported on the .outby conveyor `unit 22, thefinbyunit -2-1`2being adapted to give reciprocating movement to the belt =23 in Sa fashion ,-so .as .to convey .material therealong. The belt 23 v.is tad'apted ,to bey :supported between -the Vinby Yunit -21 `4aud the .outby unit 22 :by .means of troughing frames, not shown, `:arranged to `give a vcontour in cross section to the belt 23 in the-focm fof a Atrough so `that material mayfbe conveyed longitudinally thereof without spillipg- AThe ,inby .unit 21 consists of laterally spaced :main side frames `2.4 which :inclose Va shaker drive 25 including .a rock Shaft .26 ,extending :through the side :frames 2.4- 110.01 r Mms V2.7 are fast -to each .-end .of the rock Shaft s26 and each :is connected VVto a :link 28 which in lllrl .iSplYQtdlly,QQnrlqted :to drive rod 29 connected lto a block 3,1 disposed on :achside of a ,trough pan 32. The trough-.pan zisrsupported upon azhall Aframe 33 and extends ftowarsl the iipby cud .of .the unit 21 where .it :supports fd fgrippins mechanism indicated .generally Aby the reference numeral `d4.

pp angular vs city .df ysuch .an kOrder as tf1-impart suitdblp lineari, `Qpity and acceleration to the troughing belt 23 which is gripped by the grip bblocks 34. VrIhle precise details of the driving mechanism for the Arock shaft v*26 ,the rock argrn 27 are kno :part of this invention and so nee not be .described 1in detail. vTheicharacteristics of the motion, however, of the belt `$23 are l,such that the ,be ,lt23 moves :relatively slowly in the outby direction; "but returns rapidly in the *,inby direction, so that material i!) sa ll/ Qu -lllld9lSlQQd :by those .skilled 1in the art. The side frarpslmembprs have astage 13dextending i!! @il .Qlllby .d' etin the from to support .a pair' of girly@ protpps Yd'7 --th push .speed redirects 3.8 vvand drivingV chains 39 impart crawling lngoyernent s to a .pair Qf crawler .ift-1 mounted on I,cach side of @the side e members 24also have ,arms 42extend e inlay end or :working facs ,which provide SR. ,RE.,-.S-.f9r en ,axle L43 which zin turn supports a reeled supply 44 of the conveyor belt 23.

The

advanced :in van nby l flsnstlfpf @conveyor p mobile inby unit 21 s ,pow xto Fig- 3 o f the clrlp Qsks i3! tsppsists of a lowergrip block arm 46 thigh is piyptally connected to a pin .47

z'tppips ,rdly strom a plate 4.8 `extending downwprd :from: de wall .49 Qf'fthe trough s2. The arm 46 is drilled at the free end thereof to receive a rod 51 enciroledby ,a' .spring 52 4which .urges .a trunnion -blo-ck 53 "'havipg'lstub `trfunrriio'n shafts 54 extending therefrom, which extend an opening 56"i`n the :lower da .da pdt-.1dr armisrpsvpsa' adapts saddled 'S .QllYpydlthcrealOpg `with a shaking motion, l

substantiallyl centrally thereof and in contact with the =lower iside of :the fbelt 2-3. A `nut 59 is :threaded 'to yfthe end of the rod 51 to hold a trunnion block 53 upon the rod 51.

An upper grip block arm 61 is rocked by a bell crank 62 having an operating handle 63 and a pinned connection at to the grip -b1ok,arng61 into position against the pin 47, 'andhasalllllllitlll,blOQk 76,51 at the free end thereof held in position'by nuts 66 and 67 threaded to the arm 4&1.-

prunlpnblpslsfl hpsfaypslpoftplppisp stub shafts 68 `whit; cpivotallycnnnected to ,the-,upper end of the grip link arm 57. An upper grip block ,6.9 is pivsted its vthelipls ,grip sftp 57 spbstpptially .centrally thereof, and `is in contact with the upper surfaceof the belt 23. The lneffoenters including .the pinned connection 60 to the bell crank 62 and the center of the stub shafts 68 passing through the upper grip link 61 lie pp p lips .beraad the seater sf the pip il?, Lsp ,that when this opsratipe handle 6.31is`rQsltsl ip a gpuntsrslppkwiss d'repllop the ,stip llpk im ,.57 'Will ppcppy ,the Npssitlvll sliOWflWtli .the .sftp blppks :5,8 .and 76,9 ll'nply engaging lll@ pflsps Q;f ,tllp belt' ?tllprsbptWepp 'tp plampfsm during the rsciprppstips mpvemppt pf the .trough ,3 2- v .eip'bldclselprs .arranged tp .release the ,tppspp onlth'e "belt 23 when the tension thereon increases beyond i desired' .pipoppf- "Tihe tensin in .the belt ,23 tends Afp f pCkthp grip link capp '57 ip a plqckwse dfsctipp, .as viswpdpipfsFlg. 3, about .the itruppipp stub .shafts ,6,8 pif the Pppr .stip lilppl `drip .61- The rocking motion pf the .spip ,lipls ppp 57 is lopppssd by .th spr/ips 52 pf .the lpwpr stip -lpk ppp 4 6 Wh@ ,the tspslpnlp ,the .belt .2.3 .is olf a value fsppipf tp .Overcome the spring '.52 ,and the grip @11.1.57 ,is ,rpplfsd ip the ,manner described, the slatflpipg'pncpgefpspf pf the grip @seks .69 and 5 8 will bpllpssd slilllcsptlykto atfprd ,release pf the tppsipp of tf1@ belt L23, allier Whish peleas@ this for@ pf 'the spring 5`2i`willpds the stip hlopls@ 'apd prise mp2s its sftp ftp@ hielt 12,3 While resins-,Catas with the tfopeh .ppp 32. Y i l The :outby conveyor Aunit 2 2 consists of la frarne 'indicated generally *by` the reference :numeral 71 which is mounted tOna `pair 'of skids 72 which. provide 'spaced pppts fprm-ire iapks (ppt 'sh'pwn adapted lphepr against the mine roof" to hold 'the outby'unitp2-2 place,v The frarnelll'i's provided with extending ears v7-3 provide points of Asupport for ball franies 7 4 which Vunderlie an outby'trough' section 76. f1 he outby 1'trough section 76Vin'cludes a bottoni Yplate 77 anked by side Vwalls 78 integral `therewith. The conveyor lbelt 23 is heldin positiorrl to thebottorn plate '77 by Ymeans of angles l79, 79 each having ayertijcal leg Ybearing against lthe @side walls 78 and each having ahorizontal legv with rivets 81 passing therethrough andthrough 'the'beglt '$23 and the bottom plate 7s-7.4 Thetti'oug'h section 76 is moved with the -beltnZirir-l a load carrying direction by meansY of va 'fluid 'actuated cylinder: V'8. 2 which'has Va hingedconneotion at 83 to va pairiof vertical reinforcing 'ribs -84 fonthe'frafne 71.

Referringpow` 'to `Pig.V 2, the fluid actuated cylinder tion` at-87 to vv:abra'cket 88 held by cap screws-'89 tothe underside :of the bottom plate 77, se'e also Fig `9. 1-he fluid operated cylinder -8'2 is closed at the fluid admission -eiid thereof -by a cYInderhead 9 1, and "has a piston r952`ther'eirfwith a skirt -93 of a reduced outside diameter adadapted to *be supported upon a vreduced vdiameter portion`94v`of thel piston rod-86`, said vportion94 having a sliding Ilit with the 'inner diameter of the skirt 93. A collarl96 -is arranged lto .bear against a shoulder 97 formed at the juncture of the piston Arod 86 with the portion 94 thereofgand a spring 98 is adapted to' bear againstfthe co1lar'9 6 at 'one nend thereof and against Vthepi'ston l92 ad@ dhd discende dieser@ s @ddr-.ding the skirt 93.

A'Th'e" skirt 93 `is spaced a distance Afr orn the collar 9,6,

spacedV an equal distance from thepiston 92, so that the piston 92 may move at times relative to the piston rod 86, under conditions as will appear as this specification proceeds.

The piston rod end of the cylinder 82 is closed by a. head 99 which alords a support for an oil seal 101 encircling the piston rod 86 and a support for a bushing 102 providing a guide for the piston rod 86. A small breather passageway 103 is provided in the head member 99 and enables Ioil or air to be displaced from within the cylinder 82 upon movement of the piston 92.

vThe cylinder 82 and the piston rod 86 are adapted to be actuated so as to place tension upon the belt 23 when the shaker drive 25 of the mobile unit 21 moves the belt 23 in a direction tending to buckle same. Fluid under pressure for actuating the cylinder 82 and the piston rod 86 is supplied by a fluid pressure system indicated generally by the reference numeral 100. Said fluid pressure system consists `of a motor 104 which drives a pump 106, see also Fig. 7,' supplied with fluid from a tank ,107 by an intake line 108. The pumped fluid leaves the pump 106'by a pressure line 109 lto be delivered past a check valve 111 to an accumulator 112 where the luid is stored under pressure. Anunloading .valve 113 is connected by a line '114 branching from the pressure line 109 and is operable to discharge the pumped uid by a line 116 to the tank 107 when the pressure in the accumulator 112 reaches a value in excess of a predetermined amount.

A pressure line 117 4is connected from the accumulator 112 to a control valve 118 at a port 119 openingonto a bore 121 in the valve body 118. A spool valve member 122 is slidable within the v'bore 121 and has a reduced diameter portion 123 located between spaced lands 124 and 126 on the spool valve member 122. The spool valve member 122 is actuated by a push rod 127 connected to a link 128 which in Iturn is connected to a'rock arm 129 mounted on the motor shaft 131 of aselsyn motor.132.

When the valve 118 is in a position shown in Fig. 2 iiuid will move from the pressure line 117 past the'reduced diameter portion'123 to supply the cylinder 82 by means of a pressure line 133, to move the piston 92 and the piston rod 86 to the left. f jY 'v The spool valve vnumber 122 has a reduced diameter portion 134 defined by the land 124 and an end land 136. The Vselsyn motor 132 is adapted to rock the rockl arm `129 in a counterclockwise direction asl seen in Fig.v 2, under conditions as will appear, to move the reduced diameter portion 134`in'to register with a port 137 connecting a line 138 to tank, so as to release the pressure fromv behind the piston 92, and so that the conveyor belt 23 may move to the right on a return stroke of the` conveyor unimpeded by any residual pressure within the cylinder 82.

Referring now particularly to Fig. 1 of the drawings the mobile unit 21 is provided with means for signaling theselsyn motor'132 of the stationary unit 22, see also Figs. 2, 7 and 7A, of the necessity of placing tension on the belt 23 by the clinder 82. Such a'signaling means consists of a selsyn generator 139 having a rock arm 141 connected rigidly to a motor shaft'142'thereof, see also Fig. 9. The selsyn generator 139 is mounted on a bracket 143 extending from the stage 36 vsupporting the drive motors 37. The rock arm 141 has pin connected thereto a block 144 which slides upon a rod 146 rigidly connected to a bracket 147 extending below the trough frame 32. The rod v146 is provided with movable stops 148 and .149 whichare opposed in their movement by springs 151 and 152 respectively. The rocking movement in one direction of the rock arm 141 is limited by a stop 153 and in the other direction by a similar stop 154. It will be seen that the reciprocating movement of the belt 23 will rock the arm 141 first in one direction and then Vinthe other alternately against the stops 153 and 154. A l Y I Referring now to- Fig. 7 and 7A of the drawings, the selsyn 132 and 139 are supplied with power from'an A. C.

sourcel by means of power leads 156 and 157. Generator 139 has a rotor 158 with a winding 159 which is excited from the A. C. source. Motor 132 similarly has a rotor 161 which is excited by a winding 163 from the same A. C. source, the two windings being connected in parallel. Selsyn generator 139 has a Y-connected stator winding 164 with leads 166, 167 and 168 which are connected in parallel with a Y-connected stator winding 169`of the selsyn motor 132. It will be apparent that when the rotor 158 of selsyn 139 is rotated through any angle the rotor 161 of the motor 132 will be rotated through the same angle. The theory underlying selsyn motors and generators of the type just described is too well known lto make same necessary in lthis description, and it will appear that the selsyn generator 139 will act as a transmitter of a condition of the belt 23 at the mobile inby unit 21, while the selsyn motor 132 will act as a receiver of the condition lthen obtaining at the selsyn generator 139.

It may be noted that the power for exciting the windings 159 and 163 may be derived from any suitable A. C. source or from a motor-generator set, not shown, made a part of the mobile unit 21.

Referring now particularly to Fig. 7A, the mobile unit 21 is supplied with power from a pair of leads 171 and 172. The supply of power to the motors 37 is under the control of a. reversing drum indicated generally by the reference numeral 173 and a start-stop switch indicated generally by the reference numeral 174. When the switch 174 is moved to the start position shown a circuit will be made including a lead 176 branching from the lead 171 and including a normally closed contact 177 of a main relay having a coil 178 and a winding 179 ofv a time delay contactor. When the winding.179 is thus energized, a contact 181 thereof will close, which will complete a circuit from -the lead 171 through a normally closed overload relay contact `182 and the main relay winding 178, the circuit being completed by way of the lead 172.

, The energizing of the winding 178 closes a holding contact connected in parallel with the contact 181 and also closes a contact 183 to complete a circuit through an overload relay winding 184 and a resistance 186 connected in series with a leads 187 to armatures 188 of the drive motors 37. It will be remembered that the energization of the winding 179 causes a contact 189 thereof to open, so that the, armatures of the motors are in series with the resistance 186.

The motors 37 are series connected with elds 191, the circuits to the armatures 188 and the elds 191 including contacts 192 closed by contact bar 193 of the reverse drum 173, the lead 194 to the eld winding 191, a lead 196, contacts 197 and 198 which are closed by a contact bar 199 of the reverse drum 173 and thence by a lead 201 to the other line 172.

The winding 179 of the time delay contactor is arranged to close the contact 189 after a certain delay period, so that the resistance 186 will be cut out of circuit with the armature windings 188 and the field windings 191 of the motors 37, so as to impress full voltage thereacross, the shorting circuit including a lead 202 connected in parallel with the resistance 186 and the closed contact 189.

The main relay winding 178 will continue to be energized'by the holdingcontact 185 thereof until the startstop switch 174 is opened, at which time all the circuits controlling the motors 37 are opened. The motors 37 willA drive the inby or mobile unit 21 in a direction to place tension on the belt 23, which tension will place too great a load on the overload relay 184 causing its normally closed contact 182 to open, thereby opening the circuit'to the motors 37 irrespective of the position of the start-stop switch 174. .The overload relay 184 may be ofthe manual resetting type, so that once actuated, the motors 37 will not go through the starting cycle described until the overload relay 1,84 is rst reset manually. The operation of the reverse drumA 173 in order to motor 37 will be driven only at a reduced speed since the resistance 186 is connected in series therewith.

During this take-up movement of the belt 23 by the operation of the drive motors 37, the shaker unit 26 will continue to operate and when the proper tension is brought upon the belt 23 by operation of the motors 37, the piston rod 86 will not overtravel with respect to the cylinder 82 so that the bumper 206 will no longer close the contacts 213 and 214. The opening of said contacts will, of course, deenergize the winding of the relay 219, at the same time opening the contacts 222 and 223, deenergizing the winding 179 and opening the main Contact 183 in circuit with the motors 37.

Such operation at low speed of the motors 37 in a direction to correct the belt tension will automatically take place as the necessity therefor arises, there being no attention required of the operator to correct the tension of the belt, such being had automatically.

When the working face is advanced the shaker drive is stopped, and the grip blocks of mobile unit 21 released. The mobile unit 21 may then be advanced towards the working face and the grip blocks operated to grip the belt 23 once more. The shaker drive 2S may then be restarted and the sequence of operations previously described, repeated, automatic correction of the tension of the belt being had as needed as previously described. v

In the event of over-tensioning of the belt 23 as migh be occasioned by too great a load therein, or by overtravel of the mobile unit 21 in an inby direction, the grip blocks 34 will release in the manner previously described to correct the tension.

The mobile unit 21 may be arranged to receive the discharge from a gathering and loading machine or from the discharge boom of a continuous miner, both not shown. Alternately, the mobile unit 21 may provide a means of supplying power to a duckbill type of gathering head, the reciprocating motion therefor being provided by the reciprocating movement of the trough 32 and a suitable connection to the rock arm 27 of the shaker drive 25.

From the foregoing description of the invention it will be apparent that there has been provided a new and useful improvement in apparatus for conveying material from the working face of a coal mine or the like. While the invention has been described in terms of a preferred embodiment thereof, it is not intended that the invention be limited by the precise embodiment herein shown, nor otherwise than by the scope and terms of the claims here appended.

I claim as my invention:

l. A shaker conveyor comprising an inby unit and an outby unit supporting a material conveying belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating motion to said belt, fluid pressure means mounted on the other of said units and operable only upon the movement of said belt in a direction tending to buckle same for placing tension on said belt to prevent buckling thereof, and means actuated by the reciprocation of said bel't for controlling said fluid pressure means.

2. A shaker conveyor conprising an inby unit and an outby unit supporting a material conveying belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating motion to said belt, fluid pressure means mounted on the other of said units and -operable only upon the movement of said belt in a direction tending to buckle same for placing tension on said belt to prevent buckling thereof, means responsive to the displacement and direction of movement -of the bel't at the said one unit, and means responsive to said last mentioned means for controlling said fluid pressure means.

3. The invention -as defined in claim Z'Wherein the means for controlling 'said uid pressure means includes a control valve. Y f x 4. A 'shaker vconveyor comprising a stationary unit and a mobile unit for supporting a material conveying -belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating movement to said belt, a motor for driving said mobile unit, fluid pressure means mounted on 'the other of said units and operable only upon the movement of said belt in a direction to buckle same for placing tension on said belt to prevent buckling thereof, and means operable upon the overtravel of said 'belt at said other unit arising from the slack of said belt and the placing under tension thereof by saidruid pressure means for controlling said motor -to drive said mobile unit in a direction to take up the slack on said belt.

5. A shaker conveyor comprising a stationary unit and a mobile unit for supporting a material conveying belt having reciprocating motion, a shaker drive mounted on one of `said units for imparting reciprocating movement to said belt, a motor including a control circuit 'therefor for driving said mobile unit, uid pressure means mounted 'on the other of said units and operable only upon the movement of said belt in a direction tending to buckle same for placing tension :on said belt to prevent `buckling thereof, and switch means operable upon the overtravel of said belt at said -other unit arising from the slack of said belt and the placingl under tension thereof by said uid pressure means, said switch means being connected in said control `circuit for said mot-or 'to drive said mobile unit ina direction to take up the slack on said belt.

6. A shaker conveyor comprising a stationary unit and -a mobile unit for supporting a material conveying belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating movement to said belt, a stationary support mounted on said unit for storing additional lengths of said belt, -and means movablewith said belt and with said shaker drive for gripping said belt to cause said belt to reciprocate whilst the additional supply of said belt is held on said stationary support.

7. A shaker conveyor comprising -a stationary unit and a mobile unit for supporting a material conveying -belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating movement to said belt, a stationary support mounted on said unit for storing additional lengths of ls-aid belt, and means movable with said belt and with said shaker drive for gripping said belt to cause said belt to reciprocate whilst the additional supply of said belt is held on said stationary support, said l-as't named means Ibeing automatically releasable upon over-tension of said belt until the tension thereof is lowered to a desired value.

8. A shaker conveyor comprising a stationary unit and I a mobile unit for supporting a material conveying belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating movement to said belt, a stationary support mounted on said unit for storing -additional lengths of said ybelt, and means movable with said belt and with said shaker drive for gripping said belt to cause said belt to reciprocate whilst the additional supply of said belt is held on said stationary support, said gripping means being releasable so that an additional length of said belt may be supplied when said mobile unit is moved away from said stationary unit.

9. A shaker conveyor comprising an inby unit and an outby unit supporting a material conveying belt having reciprocating motion, a shaker drive mounted on one of said units for imparting reciprocating motion to said belt, means mounted on the other of said units and operable only upon the movement of said belt in a direction tending to buckle same for placing tension on said belt to prevent buckling thereof, and means actuated by the reciprocation of said belt for controlling said rst mentioned means.

10. A shaker conveyor comprising an inby unit and "11 an `:outlay :unitsupporting :a :material vv'conveying -b'elt n=ha1v ing reciprocating motion, a shaker drive mounted/onrone of said units for vimparting `re ':iprocating :motion 4to said b elt,.-means mounted on theotherfof said unitsand operable only `upon:the movement vof saidlbelt inadirection itendingzto .buckle same iforplacing tension on said beltlto 2 prevent p-buckling thereof, means 2responsive to lthe displacement "and V'direction o'f movement `of the be'lt at the-said one zunit, .and means responsive to sai-dlastfmentioned means-forcontrollingrsaidffirst mentioned means.

111. AA shaker aconveyor comprising a stationary unit and a mobile :unit vfor supporting Va `material conveying belt'having reciprocating motion, a-shaker drive mounted on0neof said units fiorimpartingreciprocating'movement to said lbelt, a Arnotor for driving said mobile -unit, means mounted on the other of said units and operable only -upon the -movement-of said belt in a direction to buckle same forrplacing ltension 4on said belt -to prevent buckling vthereof, and means operable upon the --overtravel ofsaid belt at said other unit arising from lthe slack of said belt and Vthe placing lundertension thereof by said first mentioned means for controlling said vmotor to drive said mobile unitin'asdirection to take up `the slack on -said belt.

12. A shaker conveyor comprising a stationary unit and ra mobile unit for supporting Aa material conveying belt having reciprocating motion, -a shaker drive mounted on one of said units for imparting reciprocating movement tto said belt, a lmotor "including a ycontrol ,circuit therefor for driving Vsaidmobile unit, lmeans mounted on the other of `said'units and voperable only'upon-th'emovement of said belt vin a direction tending to buckle same for placing tension lon-said belt toprevent buckling thereof, land switch means operable `upon `the vovertravel of said'fbelt'at said yother unit arisingfrom the slack of said 13. shakenconveyor comprising an inby =unit and an outbyeunitwsupporting armaterial conveyingbelt Vhaving `reciprocating rmovement, Ya shaker -fdrive mounted on :one of .said units :for imparting .reciprocating `motion to said lbe'lt, ysaid:shakercdrive Aplacing tension :on said lbelt in one :direction ionly of :movement fthereof, .and ameans mounted. on fthe 'otherrof 'said Aunits Lfor ,placingrtension on said Vbelt only ,during the opposite direction of :movement thereof in famount z-'suiic'ient to vprevent :buckling ithereof.

14. A shaker conveyor .comprising Tan 1inby unit :and antoutby :unit supporting a `material,conveying belt lhaving reciprocating :movement,:a shaker drive .mounted -on one of said units for imparting ureciprocating motion to said belt, ;said `shakertdrive placing :tension on said .belt in fone :direction yfonly of .movement thereof, and :means mounted :on the aother .of said -units :and :acting .independently -of zsaid .shaker fdrive for placing -tension of said belt only during the `opposite direction Iof movement thereof, Lthe tension fbeing in Iamount `sufficient to prevent buckling thereof.

15. A shaker conveyor comprising an :inby unitand an `outby .unitsupporting a material fconveying ybelt ihaving reciprocating z-movement, ya shaker drive mounted on gone ,of saidzuriits :for imparting reciprocating fmotion to ssaid belt, said shaker drive placing tension on ysaid belt ain 'one direction yonly of movement thereof, and iluid pressure means mounted on the other of said units for placing derision of said ybelt only during the OPpOSite direction -of movement thereof, said tension 'being in amount sufficient of prevent buckling 'of said Tbelt.

Germany June 1111, 1921 492,525 'Great Britain Sept. 19, '1938 'Great Britain May 5, 1949 

